The Sky This Week for October 27 to 29

The Sky This Week for October 27 to 29

First Quarter Moon arrives at 6:22 p.m. EDT. Our satellite rises in the southeast around 2 p.m. local daylight time, but it doesn’t become prominent until the Sun sets shortly after 6 p.m. (The Moon then lies due south and about one-third of the way to the zenith.) After darkness falls, the Moon’s half-lit orb appears in northeastern Sagittarius, to the upper left of that constellation’s conspicuous Teapot asterism.

Saturday, October 28

If you live in the southern tier of states, you might be able to glimpse Mercury as October ends. The innermost planet shines brightly enough — magnitude –0.4. The problem is that it rises only a couple degrees above the west-southwestern horizon 30 minutes after sunset. Use binoculars first, then, if you observe Mercury, see if you also can spot it with your naked eyes.

Sunday, October 29

Asteroid 7 Iris glows at magnitude 6.9 as it reaches opposition and peak visibility tonight. Iris lies within one binocular field of Aries the Ram’s brightest star, magnitude 2.0 Hamal (Alpha Arietis). This area stands high in the east by midevening. The best way to find Iris is to look 1.5° south of Hamal and 1° south of the star Kappa Arietis, which glows at magnitude 5.0. To confirm a sighting, sketch the star field with Alpha, Kappa, and several stars south of them. Return a night or two later and identify the point of light that changed position. That “star” is Iris.